Chiropractic adjustments of the spinal vertebrae of a body involve the application of pressure or force in a known manner directly to the body by the hands of a chiropractor or by a chiropractic adjustor apparatus. Examples of such chiropractic adjustor apparatuses found in the prior patent art are those disclosed in U.S. Pat. No. 4,716,890 to Bichel and U.S. Pat. No. 4,841,955 to Evans et al.
Another example of a prior art chiropractic adjustor apparatus is described in the Applicant's earlier patent, U.S. Pat. No. 6,537,236. This patent describes an apparatus that includes a housing, a handle on the housing, a trigger reciprocally mounted to the handle, an electronic control module provided in the handle and activated by depression and release of the trigger, and an elongated force-transmitting shaft reciprocally mounted through the housing. An electromagnetic drive mechanism is disposed in the interior cavity of the housing and connected electrically to the electronic control module. The chiropractic adjustor is operable by the actuation of the trigger and the return action of a compressible spring near the rear portion of the housing, causing the shaft to transmit vibratory energy to the human body.
The electromagnetic drive mechanism includes a spool with stationary electrical windings supported in the interior cavity of the housing and a stator mounted on the shaft and disposed within a bore of the spool in an electromagnetically coupled relationship with the electrical windings about the spool. Depressing the trigger activates the electrical control module to apply predetermined pulses to the electrical windings so as to actuate the stator and thus the shaft into a repetitive reciprocal vibratory type of movement along a longitudinal axis of the shaft and relative to the housing.
One operation performed by a chiropractor is manipulation of the spine. A U-shaped force-transmitting head is commonly fitted to the shaft for this operation. The U-shaped head is placed to straddle the spine such that one arm of the U is on each side of the spine.
During operation, many of the prior art devices tend to rotate, or twist, out of the user's grip, as a result of the rotational components of the force exerted on the shaft by the electromagnetic drive mechanism, requiring the operator to exert significant effort to hold the device substantially perpendicular to the patient's vertebrae. The earlier patent of the Applicant, U.S. Pat. No. 6,537,236, describes a mechanism to resist such rotation so that the device can be held in the proper position along the patient's spine. The mechanism described is a pin mounted across a forward portion of the shaft that moves with the shaft. The pin moves in a slot formed in a sleeve attached to the housing of the adjustor. The pin and slot combination allows the shaft to move longitudinally but prevents rotation. The description in U.S. Pat. No. 6,537,236 is incorporated herein by reference.
It has been found that it is desirable to allow some degree of rotation of the force-transmitting head during operation of the chiropractic adjustor. Therefore, it is an object of this invention to provide a device that allows a controlled amount of rotation of the head during operation. It is a further object of this invention to provide a head that depresses a controlled distance while rotating a controlled distance. It is a further object to provide a force-transmitting head that can be rotated to the right or left a desired amount.